Dr Merrivale Carr, the finest detective in 1920s England, is preparing to wrap up another investigation while his young assistant, Henry Ransom, observes and takes notes. Two of Lord Farthingale’s house guests have been murdered, and Dr Carr accuses society hostess Glenda Neil, whom he claims killed them to cover up her past as a male impersonator named Kitty Kickshaw on Broadway. However, the Doctor and Rose unexpectedly burst into the drawing room and claim that Dr Carr is wrong; the house is in fact infested with deadly, invisible aliens. The house guests believe the new arrivals to be mad until something invisible lifts young Bart Faversham from his feet and throws him headfirst into the hearth with deadly force. The survivors retreat to the billiard room, where the Doctor explains that an alien spaceship is trapped between real space and the Vortex; the crew are trying to engage the damaged drive, and the side-effects of the energy are wreaking havoc in the manor house. The Doctor uses his sonic screwdriver to communicate with the crew, and he and Rose are transported to the alien ship, where they find that the occupants were killed in the crash and the ship’s computer is trying to engage the engines automatically. The Doctor repairs the damage and sends the ship on its way, and he and Rose return to the house and depart in the TARDIS. Dr Carr, rather embarrassed, asks Henry not to chronicle this particular case.

The Doctor and Rose land on an alien planet whose inhabitants wear masks enabling them to share their thoughts as a telepathic community. The spokes-unit for the community mind, Makassar, asks the Doctor to speak on its behalf to the alien representatives who have come to see the masks for themselves, but the Doctor refuses. However, when he admits to Rose that his own people had a system like this, called the Matrix, Rose realises that this planet reminds him of the home he’s lost. The Doctor realises that she’s right and goes to apologise to Makassar while Rose gets some sleep -- but she is confronted by a ghost-like phantom of a man wearing a mask, and when she tries to find the Doctor, she is attacked by Units who force a mask onto her face. The Doctor is also attacked by Units and forced to wear a mask, but Makassar finds it more difficult to take over the Doctor’s mind than he’d anticipated, and the Doctor is able to fight him off and rescue Rose from the gestalt. The Doctor places her in a dreamscape fashioned from Rose’s memories of the Powell Estate, where she gets her bearings and tells him about the ghost, who is presumably a rebellious Unit. The Doctor sends her out to find the ghost, and when she is attacked by Units, she calls out to the one who tried to contact her. While Makassar’s attention is divided, the Doctor manages to overpower him and draws on the power of the gestalt to generate his own ghost, one with some physical substance. Before Makassar can stop him, the Doctor removes his control mask and replaces it with one of the masks worn by the ordinary Units. The other Units are freed, including the Doctor and Rose, while Makassar is trapped in a mental feedback loop, capable only of sending orders to himself.

Phil Tyson, a 26-year-old janitor at a Cheeky Chicken franchise, is kidnapped by aliens who believe him to be the reincarnation of Shogalath, a war criminal responsible for overthrowing the Vandos Imperium. Before the aliens can execute him, however, the Doctor and Rose intervene, distract the Tribunal and rescue Phil. As they flee back to the TARDIS, the panic-stricken Phil holds tight to his bucket full of cleaning fluid, the only link back to his real, normal life. Rose manages to calm down Phil and get him running, but just as they reach the TARDIS, they are attacked by the squid-like bailiffs, who prepare to eat the Doctor and Rose alive. Phil flings his bucket of soapy water at the aliens, who are incapacitated by the ammonia in the cleaning fluid. The Doctor, Rose and Phil escape in the TARDIS, but the Tribunal contact them and threaten to incinerate the whole of Great Britain unless Phil is returned to them. Phil volunteers to give himself up, but the Doctor had already sabotaged the ship’s offensive systems in case the Tribunal get nasty, and when the aliens attempt to carry out their threat, their ship explodes. The Doctor and Rose take Phil back to Earth, and the Doctor reveals that Shogalath was in fact a peaceful religious figure who toppled a corrupt dictatorship in a bloodless revolution. Phil departs with a new appreciation for life.

The Doctor and Rose arrive on a planet where the rain has become sharp enough to cut through human skin. Most of the human colonists have already been killed, and the few survivors are huddled in flimsy shelters, waiting for the end. The Doctor and Rose seek shelter with a family of three, although the father, Jack, doesn’t want to let them in. At one point, Jack tries to force the newcomers outside so the rain will take them and stop trying to break through his family’s roof, but he stops when his wife, Susie, informs him that she intends to leave him whether they survive this or not. As Jack and Susie argue over whose fault it is that they’re stuck here, the young boy, Andy, watches the other colonists die, numbed to the horror and just watching in case something interesting happens. The family has run out of drinkable water, and despite the risk, Susie collects some of the deadly rain in a saucepan and boils it until it stops thrashing about. The Doctor thus realises that the rain is alive and is just lashing out at the colonists who had been drinking and killing it. He leaves the shelter to communicate with the rain, hoping to convince it to let him and Rose go, but Rose insists that he speak on behalf of the family as well. Jack, Susie and Andy are now the only colonists left alive on the planet, but the Doctor convinces the rain to let them return to their ship and leave. Andy, inspired by the risk the Doctor that took, vows to overcome his fears and grow up to be a true space traveller seeing the wonders of the Universe, and not just a frightened boy hiding away in a shelter.

Time-placement: The illustrations make it harder to place, but there are clues. The Doctor's jumper looks to be blue, and Rose's hair is styled as per Rose to World War Three, but the clothing looks similar to that seen in Dalek. The best suggestion for placement is between Winner Takes All and Art Attack!.

12-year-old Sally Sparrow is assigned to write the story of her Christmas holidays for her English homework. While staying with her aunt in Devon, she starts to pick at the peeling wallpaper in her guest room, and finds a message specifically written to her, asking for help -- and yet dated Christmas Eve 1985, eight years before she was born. In a box of photographs, Sally finds a picture of that year's Christmas party, in which a man is holding up a sign asking her for help. Further instructions are written under the wallpaper, and Sally follows them and thinks up a random number, which she then finds carved into the bark of the furthest tree in the garden. Thus convinced that this is really happening, Sally follows the instructions behind the wallpaper and tracks down a videotape in which the man, the Doctor, speaks directly to her, explaining that his time machine hiccoughed and leapt ahead 20 years in Time, leaving him stranded in 1985. He can communicate with Sally because he’s reading the story she’s going to write for her Christmas homework, which he claims was given to him by a beautiful female spy who saved his life some time in the future. As Sally watches, the Doctor’s TARDIS materialises on the screen behind him -- and Sally’s future self, two hours older, steps out, having followed the instructions on the video and piloted the TARDIS back to the Doctor. Sally writes up the story for her homework, after which she will go out to the shed where the TARDIS is waiting; she is inspired now that she knows what her future holds, for the Doctor has told her that the beautiful female spy from the future was named Sally Sparrow.

Time-placement: The Doctor's jumper colour is black, and there's no sign or mention of Rose. Thus, likely before meeting her in Rose, or even possibly at the end of this episode, as a quick side trip before popping back to convince Rose to join him.

Source: Cameron Dixon. With thanks to Cameron J. Mason for the time-placement notes.